This invention relates to the medical field and more particularly to catheters.
Catheters are used in the medical field to introduce fluids (i.e., liquids and gases) to and to remove fluids from patients. The size (length and diameter), material of construction, and features (e.g., size and location of drainage holes) of a catheter will vary depending on where the catheter is to be inserted, the fluid being carried by the catheter, and the size of the patient. Catheters and their use are described in U.S. Pat. Nos. 3,190,290, 3,295,527, and Re.25,788 and in Chapter 6, Frumkin, "Tube Thoracostomy," of Roberts and Hedges, Clinical Procedures in Emergency Medicine (W.B. Saunders Company, 1985), all of which documents are hereby incorporated by reference.
A continuing problem with the use of catheters is properly positioning them in the patient, for example, in the pleural cavity. If a thoracic catheter is to be used to remove gas from the pleural cavity, the distal (far) end of the catheter, which is inserted into the patient, is directed towards the top (apex) of the cavity (as shown in FIGS. 1 and 2). If liquid is to be removed, the distal end is directed downward towards the bottom of the pleural cavity.
The usual procedure for inserting and positioning the catheter involves making an incision between the appropriate ribs and pushing the catheter into the pleural cavity using a clamp (e.g., a Kelly clamp), which is inserted into the same opening as that through which the catheter passes. The clamp also helps direct the catheter to a superior (higher) or inferior (lower) position.
It would be advantageous if the catheter, which is flexible, could itself change its curvature before or after insertion to point in either an up or down direction and maintain that curvature while the catheter is in the patient. That would facilitate positioning of the catheter, would reduce the chance of misdirecting the catheter into adjoining body structures, and would help the catheter maintain its position while it is in the patient.